Try looking thru these two pages for Legacy extensions. https://github.com/JustOff/ca-archive http://legacycollector.org/firefox-addons/

Note that it isn't safe to use an outdated and no longer supported Firefox 56 version. *https://www.mozilla.org/security/known-vulnerabilities/firefox.html You can use code in userChrome.css to restore a lot of Classic Theme Restorer features. *https://github.com/Aris-t2/CustomCSSforFx *https://github.com/Aris-t2/CustomCSSforFx/issues/2 *https://github.com/Aris-t2/CustomCSSforFx/releases/ *https://github.com/Aris-t2/CustomCSSforFx/tree/master/classic/css/tabs *https://github.com/Timvde/UserChrome-Tweaks/tree/master/tabs